1. Field of the Invention
The invention relates to a pneumatic vehicle tire, in particular for utility vehicles, having a carcass, a belt which is constructed radially outside the carcass and a profiled tread which is constructed radially outside the belt on the belt. The belt is formed from at least three belt plies arranged lying one on top of the other from the radial inside to the radial outside, and the radially inner belt ply and the radially outer belt ply are working plies with parallel strength members, in particular made of steel, which are embedded in rubber. When viewed in the circumferential direction U of the vehicle tire, the strength members of the one working ply have an opposing axial direction of inclination to the strength members of the other working ply. Further, the belt ply which is arranged between these two working plies is a belt ply which is embodied or formed as a zero-degree ply with parallel strength members which are embedded in rubber and which enclose in their orientation an angle β where 0°≦β≦5° with respect to the circumferential direction U.
2. Discussion of Background Information
Conventional pneumatic tires for utility vehicles usually have a four-ply belt with what is referred to as a triangular configuration in which two working plies are arranged one on top of the other in the radial direction, the steel cords of which are at an angle of approximately 18° to 30° with respect to the circumferential direction. The steel cords of the one working ply and those of the second working ply are inclined in different axial directions A. As a result, the working plies form a diagonal assembly. In such belts there is usually a belt ply embodied or formed as a barrier ply which is located under the working plies, the steel cords of which are at an angle of 50° to 65° with respect to the circumferential direction, as a result of which the cords of the working plies and of the barrier ply form a triangular assembly. In addition, usually an additional protective ply which forms the fourth belt ply is formed above the two working plies, the steel cords of which protective ply are also at an angle of approximately 15° to 30° with respect to the circumferential direction of the vehicle tire. Such belts have a limited circumferential strength. The possibility of moving the belt edges, which this provides, can have an adverse effect on the durability of the tire. The belt can also be subject to radial expansion during operation. This growth can lead to excessive unequal wear of the tire.
It is also known to form pneumatic tires for utility vehicles with a four-ply arrangement with a radially inner barrier ply with steel cords which enclose an angle of approximately 50° to 65° with respect to the circumferential direction, with two working plies which are formed over the barrier ply and which form in a conventional way a diagonal assembly of their steel cords with an orientation of the steel cords of in each case approximately 18° to 30°, and with a fourth belt ply which is formed radially outside the two working plies on the outer working ply and which is embodied or formed as what is referred to as a 0°-ply. The strength members are composed of steel cords and are oriented essentially in the circumferential direction with an angle of 0° to 2.5° with respect to the circumferential direction. In such formations, the circumferential strength of the belt is increased, which has a positive effect on the durability of the belt. However, the influence of the 0°-ply is limited essentially to the radially outer working ply. However, the inner working ply is formed with residual mobility, still with adverse effects on the durability and wear.
Furthermore, occasionally a formation of a pneumatic tire for a utility vehicle with a belt arrangement in which a 0°-ply is formed radially between the two working plies has been proposed. The two working plies continue to be formed in the diagonal assembly in these proposed embodiments and their steel cords are oriented with angles of, in each case, approximately 18° with respect to the circumferential direction. Although this embodiment permits a high level of circumferential strength and improved durability and an improved wear performance compared to a conventional pneumatic tire for a utility vehicle, the durability is still limited with such an embodiment since large shearing forces occur between the three plies as a result of the very acute angles of the strength members which are respectively formed both between the outer working ply and the 0°-ply and between the 0°-ply and the lower working ply. These shearing forces can have a direct adverse effect on the durability of this ply configuration.